1. Field of the Invention
The present invention relates to a spindle motor and more specifically to a spindle motor for use in a disk drive apparatus.
2. Description of the Related Art
Spindle motors (hereinafter referred to simply as “motors”) have often been installed in disk drive apparatuses, such as hard disk drive apparatuses. In an outer-rotor motor disclosed in JP-A 2004-135467, a rotor assembly includes a cup-shaped rotating hub body and a driving magnet, while a stator assembly includes a stator core and driving coils wound on the stator core. The driving magnet is fixed to an inner circumferential surface of an annular wall portion of the rotating hub body, and is arranged opposite to an outer circumferential surface of the stator core. While the motor is driven, a magnetic action is produced between the driving magnet and the driving coils. JP-A 2008-97803 also discloses a motor in which a permanent magnet is arranged opposite to an outer circumference of an electromagnet.
In recent years, there have been a demand for a reduction in thickness of disk drive apparatuses, and also a demand for a further reduction in thickness of motors installed in the disk drive apparatuses.